Analog-to-digital conversion with noise injection via wavefront multiplexing techniques

ABSTRACT

A novel noise injection technique is presented to improve dynamic range with low resolution and low speed analog to digital converters. This technique combines incoming signal and noise signal with wave front de-multiplexer and split into several channels. Then low resolution and low speed analog to digital converters are used to sample each channels. All signals are recovered using wave front multiplexer. For advanced design, ground diagnostic signals with optimizing processor can be added to guarantee recovery quality.

RELATED APPLICATION DATA

This application is a continuation of application Ser. No. 12/985,044,filed Jan. 5, 2011, now pending, which claims the benefit of U.S.provisional application Ser. No. 61/381,381, filed Sep. 10, 2010.

BACKGROUND

1. Field

The present invention relates to architectures and designs of digitalsystems. More specifically, but without limitation thereto, the presentinvention pertains to an electronic signal conversion system thatutilizes a noise injection system in order to maintain or increasesignal resolution and increase the dynamic range. The present inventionalso offers a more time-efficient conversion as well as a morecost-effective conversion method.

2. Prior Art

The following is a tabulation of some prior art that presently appearsrelevant:

U.S. PATENTS

Pat. No. Kind Code Issue Date Patentee 5,077,562 1991-12-31 Chang et al.5,630,221 1997-05-13 Birleson 6,049,251 2000-04-11 Meyer 6,526,139 Bl2003-02-25 Rousell et

NON-PATENT LITERATURE DOCUMENTS

Estrada, A.; Autotestcon, 2007 IEEE, “Improving high speed analog todigital converter dynamic range by noise injection”.

Currently in the electronics field, conversions between digital andanalog signals are necessary for many day-to-day electronic operations.Analog signals are signals that utilize properties of the medium toconvey the signal's information, essentially used in its original form.In particular for the field of electronics, an analog signal is taking asignal and translating it directly into electronic pulses. On the otherhand, a signal is considered digital when it is processed into discretetime signals, usually in the form of a binary code (Is and 0s instead ofa continuously variable function as found in analog signals). Nowadays,although nearly all information is encrypted digitally, analog signalscommonly function as carrier signals for information transmission.

As a result, conversions between analog and digital signals for modernelectronics are a common occurrence. For example, portable cellularphone signals are broadcast in the analog format and need to beconverted to a digital signal within the phone itself for practical use.

Television signals are also transmitted in the analog spectrum and haveto be converted to digital format for signal processing.

A key performance index of conversion from analog to digital (A/D) isthe dynamic range, which is the ratio between the smallest and largestpossible values of changeable quantities. Additionally, only signalstrengths within the specified dynamic range can be detected. As aresult, the dynamic range that is factored into A/D circuit design isrequired to be reasonably wide, and in some cases, to be as wide aspossible. For instance, color perceptible to the human eye ranges from4.28×10¹⁴ Hz (hertz) to 7.14×10¹⁴ Hz. If, for example, a TV's dynamicrange cannot cover this spectrum, the quality of the TV signal willdegrade as it cannot show all the colors in the received TV videosignal.

Utilizing such wide dynamic ranges has several issues. While higherdynamic range means better precision and resolution of digital signals,the higher dynamic range also necessitates more expensive and preciseequipment. There are cases where it is impossible to implement suchdevices either because it is impractical or too costly, such as inmobile devices.

Additionally, analog-to-digital conversions have an issue with unwantednoise being introduced into the signal. One source of noise is theconversion itself, as an analog signal is changed to a format thateliminates some of the fine resolution of the signal. Because of this,research has been performed to increase the dynamic range ofanalog-to-digital converters without changing the resolution, as well asreducing unwarranted and unwanted noise. The present embodiment of theinvention aims to mitigate both of these factors in A/D converters byintroducing a “noise” injection to essentially cancel out any unwantednoise as well as maintain a high dynamic range so that resolution is notlost in the conversion.

SUMMARY OF THE INVENTION

The present invention is a noise injection system for the purpose ofeliminating unwanted noise while maintaining a high dynamic range foranalog to digital conversions, comprising: a wave front de-multiplexer,multiple analog-to-digital converters and a wave front multiplexer.

The noise injection system performs as follows. Multiple input signalstreams, noise injection streams, and a ground are all connected to awave-front multiplexer, where the signal and noise signal outputs areconnected to a multiplexer. Here, the signals are multiplexed (combined)into N data streams, each with a signal component of all inputs. Themultiplexer output lines are transmitted to A/D converters. Afterconversion to digital format, the sampled digitized signals aretransmitted to a wave-front de-multiplexer, where the data streams arerecovered into output signals matching the inputs. These signals arethen reconverted from digital to analog if necessary.

Through injecting noises which could be eliminated by filtersafterwards, the present invention enhances signal strength whilemaintaining a high dynamic range. Weak signals out of the A/D converterdynamic range are now able to be detected because of added noise. Insuch a way, the signals' dynamic range is increased. Additionally,injecting noise also has the benefit of cancelling out any unwantednoise, thus increasing clarity and signal resolution.

An alternative embodiment of the present invention involves utilizing anoptimization processor that is connected to the wave-frontde-multiplexer. Samples of the signals being processed are sent to theprocessor, where an optimization loop adaptively adjusts the strength,phase, and wave front vectors of the noise in order to cancel out theunwanted noise. After processing, the signals are re-introduced into thesignal streams for proper cancellation of unwanted noise.

With the proposed noise injection system, the dynamic range of theanalog-to-digital conversion system can be accommodated with theinjected noise level without redesigning the system. Furthermore, thesignal converters in this invention process fewer bits of data, thusreducing power requirements, cost and complexity.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an illustration of an analog/digital conversion system with anattached optimizer

FIG. 2 is an illustration of an alternative implementationanalog/digital conversion system

FIG. 3 is an illustration of another alternative implementation of theconversion system

DRAWINGS Reference Numerals

102a Incoming signal (analog) 102b Incoming signal (digital) 104a Noiseto inject (analog) 104b Injected noise (digital) 105a Ground, no signal(analog) 105b Ground, no signal (digital) 106a Ground, zero (analog)106b Ground, zero (digital) 108 Wave front multiplexer 110a, Analog todigital converter b, c, d 112 Wave front de-multiplexer 114 Optimizer

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention relates to the architecture and design ofelectronic systems, and, in particular to electronic signal conversionhardware architecture and design.

An implementation of one embodiment is shown in FIG. 1. In thisparticular embodiment, there are 4 input ports with 4 signal inputsincluding: incoming signal 102 a, injected noise signal input 104 a, andtwo grounded signals 105 a, 106 a, are connected to multiplexer 108. Theinput ports in the actual implementation may vary, and not limited to 4input ports. The injected noise signal 104 a and incoming signal 102 awill be split in wave-front multiplexer 108 and mixed with each other inorder to improve dynamic range of the whole system. Ground 105 a and 106a will be used as diagnostic signals.

Wave-front multiplexer 108, equally splits and mixes M input signals toform N output signals, where, in this embodiment, M and N are both 4.Each of mixed N signals contains information from all M input signals.Each output of N signals maintains a fixed relative phase difference andN output signals form a wave front vector. For example, in case of FIG.1, if I use a 4-point Fast Fourier Transformer (FFT) as a wave frontmultiplexer, then the phase difference between each output signal ise^(−iπ/2). The wave front vector is [1, e^(−iπ/2), e^(−iπ), e^(−i3π/2)]This wave front vector will be used to recover the mixed signals.

Thus, after wave front multiplexer 108 processes the N inputs, 4 outputsignals are already incoming signals mixed with proper noises. If FFT isused as a wave front multiplexer, each channel only possesses A/Dbandwidth of the original signal. As a result, cheap, low speed and lowresolution A/D converters 110 a, 110 b, 110 c and 110 d are used tosample these signals. After conversion, the signals are all in thedigital format.

A wave front de-multiplexer 112 performs the inverse process of wavefront multiplexer. The de-multiplexer 112 is used to recover the mixedsignals to the original input signals in the digital domain. Forexample, if FFT is used previously, an Inverse Fast Fourier Transformer(IFFT) will be used here. After this, an incoming signal in digitaldomain 102 b, an injected noise in digital domain 104 b, ground indigital domain 105 b and 106 b are recovered.

All signals are recovered due to the wave front vector which representsphase differences among signals. Therefore, if any distortion occurredin previous steps, the wave front vector will be distorted. However,with the help of optimizer 114, even if signals are distorted, recoverycan still be successful. By using diagnostic signals ground 105 a and106 a, if signal recovery is successful, the recovered signals 105 b and106 b should be perfectly zero. Optimizer 114 adaptively adjusts thewave front vector until the signals 105 b and 106 b reach zero. Thus,any previous distortion is compensated for, and the output signalsexhibit improved clarity than without the present invention.

Alternative Embodiments

An alternative embodiment of the noise injection system is shown in FIG.2. Incoming signal 102 a and injected noise 104 a input signals in thisembodiment. The rest of this embodiment is the same as the mainembodiment. But optimizer, since there is no reference signal such as105 a or 106 b, quality of the output signal cannot be determined.

Another alternative embodiment of the noise injection system is shown inFIG. 3. The input signals include signal 102 a, injected noise 104 a andone grounded signal 105 a or 106 a. The rest of this embodiment is thesame as main embodiment but optimizer. Signal 105 b can be used as adiagnostic signal. It is to indicate the quality of the output signal102 b.

The invention claimed is:
 1. A method for processing signals comprising:receiving a first signal in an analog format; receiving a second signalin an analog format; creating a third signal containing information fromsaid first and second signals; creating a fourth signal containinginformation from said first and second signals; sampling said third andfourth signals to be in a digital format; and after said sampling saidthird and fourth signals, creating digital representations of said firstand second signals based on said third and fourth signals.
 2. The methodof claim 1 further comprising receiving a fifth signal in an analogformat, creating a sixth signal containing information from said first,second and fifth signals, wherein said third signal further containsinformation from said fifth signal, wherein said fourth signal furthercontains information from said fifth signal, sampling said sixth signalto be in a digital format, and then creating a digital representation ofsaid fifth signal based on said third, fourth and sixth signals, whereinsaid creating said digital representations of said first and secondsignals based further on said sixth signal.
 3. The method of claim 1further comprising providing a first processor to perform the steps ofsaid creating said third and fourth signals, and providing a secondprocessor to perform the step of said creating said digitalrepresentations of said first and second signals, wherein said secondprocessor is configured to perform an inverse process of said firstprocessor.
 4. The method of claim 3, wherein said first processorcomprises a Fourier transformer, and said second processor comprises aninverse Fourier transformer.
 5. The method of claim 3, wherein saidfirst processor comprises a fast Fourier transformer, and said secondprocessor comprises an inverse fast Fourier transformer.
 6. The methodof claim 1, wherein said creating said digital representation of saidsecond signal comprises recovering said digital representation of saidsecond signal.
 7. The method of claim 1, wherein said creating saiddigital representation of said second signal comprises recovering saiddigital representation of said second signal into zero.
 8. The method ofclaim 1, wherein said second signal comprises a ground signal.
 9. Themethod of claim 1, wherein said second signal comprises a diagnosticsignal.
 10. The method of claim 1, wherein said second signal comprisesa noise-injection input.
 11. The method of claim 1 comprising providingmultiple analog-to-digital converters to perform the step of saidsampling said third and fourth signals.
 12. A method for processingsignals comprising: receiving a first signal in an analog format;receiving a second signal in an analog format; receiving a third signalin an analog format; receiving a fourth signal in an analog format;creating a fifth signal containing information from said first, second,third and fourth signals; creating a sixth signal containing informationfrom said first, second, third and fourth signals; creating a seventhsignal containing information from said first, second, third and fourthsignals; creating an eighth signal containing information from saidfirst, second, third and fourth signals; sampling said fifth, sixth,seventh and eighth signals to be in a digital format; and after saidsampling said fifth, sixth, seventh and eighth signals, creating digitalrepresentations of said first, second, third and fourth signals based onsaid fifth, sixth, seventh and eighth signals.
 13. The method of claim12 further comprising providing a first processor to perform the stepsof said creating said fifth, sixth, seventh and eighth signals, andproviding a second processor to perform the step of said creating saiddigital representations of said first, second, third and fourth signals,wherein said second processor is configured to perform an inverseprocess of said first processor.
 14. The method of claim 13, whereinsaid first processor comprises a Fourier transformer, and said secondprocessor comprises an inverse Fourier transformer.
 15. The method ofclaim 13, wherein said first processor comprises a fast Fouriertransformer, and said second processor comprises an inverse fast Fouriertransformer.
 16. The method of claim 12, wherein said creating saiddigital representation of said fourth signal comprises recovering saiddigital representation of said fourth signal.
 17. The method of claim12, wherein said creating said digital representation of said fourthsignal comprises recovering said digital representation of said fourthsignal into zero.
 18. The method of claim 12, wherein said fourth signalcomprises a ground signal.
 19. The method of claim 12, wherein saidfourth signal comprises a diagnostic signal.
 20. The method of claim 12,wherein said fourth signal comprises a noise injection input.